1. Field of the Invention
The invention is directed to a downhole double acting pump for use in wells. More particularly, the invention is directed to a downhole double acting pump for pumping well fluids from a reservoir to the surface of the well.
2. Prior Art
In the production of well liquids it is often necessary to utilize means, other than reservoir energy, to lift the liquids to the surface of the well. Various methods have been used for this purpose, including pumps that are placed within the bore of production tubing extending into the production zone. The pump would be located below the surface of the well liquids and driven by some external force to force the liquids to the surface of the well.
Typical of the prior art pumping devices is the pump taught in U.S. Pat. No. 3,617,152, issued to Leslie L. Cummings. There is shown an automatic well pump utilizing compressed power air or gas to displace well production liquids from the well bore. This pump is referred to in the art as a single action pump and requires relative high pressures in order to lift well liquids to the surface of the well.
A well pump requiring hydraulic pressure for operation is taught in U.S. Pat. No. 4,084,923, issued to George K. Roeder. In this pump, the pistons are driven by more than one engine. The invention uses a hollow piston rod to supply power fluid to a lower engine.
It has been a goal of those skilled in the art to develop a double acting pump that will operate on a relatively small power requirement and which could be placed at relatively deep depths in a well. In addition, it would be desirable to provide a pump which could be used in through the flow line (TFL) serviced wells. This would allow use of the pump in a plurality of wells which have flow lines terminating at a single production platform, such as found in off-shore oil production.